Early selection for spike fertility index increases yield of advanced generations in bread wheat

Spike fertility index (also known as fruiting efficiency) at maturity (FEm: grain number per spike g(-1) spike chaff at maturity) and spike harvest index (SHI: grain weight per spike g(-1) spike chaff weight at maturity) are considered promising selection criteria for improving grain yield (GY) in bread wheat (Triticum aestivum L.). However, their usefulness in early generations remains to be established. Here, a population derived from a cross between 'Baguette 10' and 'Klein Chaja' was evaluated from early generations (F-2-F-3) to recombinant inbred lines (RIL). Associations of FEm and SHI measurements between early generations and RIL were established. Also, responses in grain number m(-2) (GN) and GY in the RIL after simulated selection for high FEm or high SHI in the F-2-F-3 were assessed. Positive correlations were found in FEm measured in the F-2-F-3 vs. in the RIL (r = .32, P < .05) and SHI measured in the F-3 vs. in the RIL (r = .26, P < .05). After selection for high FEm in the F-2-F-3, responses in GN were always positive: GN increased by 5.1-22.1% depending on the selection strategy. Responses in GY were positive in three out of four selection strategies, averaging -1.3-2.1%. Responses to selection in GN and GY in the RIL using SHI as a selection criterion in the F-2-F-3 were negative or neutral. Our results support the use of FEm as a selection criterion in early generations for increasing GN and GY in advanced generations of bread wheat-breeding programs.

Automated summary

The spike fertility index and spike harvest index are promising selection criteria for improving grain yield in bread wheat. This study shows that using these criteria in early generations can increase grain number and yield.